The Femoral Head of Patients with Hip Dysplasia is not as Osteogenic as Iliac Crest Bone Location

Abstract

When Total Hip Arthroplasty (THA) is required in a patient with developmental dysplasia of the hip (DDH), bone defi ciency in the acetabular roof often remains a problem. The iliac crest (IC) has long been the preferred source of autograft material, but graft harvest is associated with frequent complications and pain. Autologous bone graft can also be obtained from the femoral head (FH) for reconstruction of the acetabulum in hip arthroplasty. However, in certain challenging clinical scenarios, incorporation of the femoral head autograft appears less successful than the iliac crest autograft. The difference in potential for proliferation and osteoblastic differentiation between the two sites has still not been evaluated; therefore, it is not known how to compensate for this difference when it is present. We designed this study to evaluate the number of mesenchymal stem cells (MSCs) in both the iliac crest and femoral head of the same patient. We also determined the best operating room procedure for loading the femoral head with MSCs to achieve equivalent numbers of MSCs as in the IC. Twenty patients (8 men and 16 women) undergoing THA for DDH were enrolled in the study. The mean age was 55.5 years (range 41-65 years). Bone marrow aspirates were obtained from three depths within the femoral head and the aspirates were quantifi ed relative to matched iliac crest aspirates that were obtained from the same patient at the same time. The cell count, progenitor cell concentration (cells/ mL marrow), and progenitor cell prevalence (progenitor cells/million nucleated cells) were calculated.Aspirates of FH marrow demonstrated less concentrations of mononuclear cells compared with matched controls from the iliac crest. Progenitor cell concentrations were consistently lower in FH aspirates compared to matched controls from the iliac crest (p = 0.05). The concentration of osteogenic progenitor cells was, on average, 40% lower in the FH aspirates than in the paired iliac crest samples (p = 0.05). However, with bone marrow aspirated from the iliac crest, we were able to load the femoral head autograft with suffi cient MSCs to obtain the same number as present in an iliac crest. With concentrated bone marrow from the IC, supercharging the femoral autograft with MSCs to numbers above that present in the IC was possible in the operating room, and the number of MSCs supercharged in the femoral head was predictable.Based on these fi ndings we suggest that FH graft supercharged with BM-MSCs from the IC is comparable to IC graft for osseous graft supplementation especially in THA for patients with DDH.